Streptomyces species are filamentous Gram-positive bacteria, not fungi, and are thus out of place here. However, they occur in the same habitats as fungi and are superficially similar. The filaments and spores are very small (usually 1 um or less in diameter). The spores are formed by the fragmentation of the filaments and are borne in straight, wavy, or helical chains. The colonies are slow-growing and often have a soil-like odour. In fact, the characteristic odour of soil may be due to the abundance of Streptomyces species growing there. Common in soil, plant debris, dung, house dust, and many other habitats.
Classification: Streptomycetaceae. Ref: Buchanan and Gibbons 1974; Holt, 1994; Waksman 1961